1. Field of the Invention
The present invention relates to the field of controlled flow, exhaust manifold systems and, more particularly, to apparatus for controlling the flow of exhaust gases from a single missile being fired in a multi-missile canister and directed into a common exhaust gas manifold or plenum tube connected thereto.
2. Description of the Related Art
In certain military applications, particularly on warships having missile firing capability, the missiles are stored in a series of vertically oriented chambers closely adjacent one another. Exhaust gas outlets are normally provided to duct rocket exhaust gases generated during intended or accidental rocket ignitions to a safe location. In such installations, manifolding of a number of chambers into a common exhaust duct or plenum tube has become conventional.
There have been a number of approaches to the problems attendant upon the use of a common exhaust duct with a plurality of missile storage chambers. It is important to be able to block the exhaust gases from a missile which is being fired from blowing out through the individual chambers of other missiles. This is commonly accomplished by the use of doors or hinged panels which can open into the plenum chamber from the force of an impinging missile exhaust for the chamber containing the missile being fired and which can close off the passage at the base of a missile chamber opening into the exhaust plenum for other missiles.
Eastman U.S. Pat. No. 2,445,423 discloses apparatus having a plurality of individual missile chambers coupled to a common plenum chamber with a plurality of hinged, spring-loaded doors at the juncture of each individual missile chamber with the plenum tube. These doors open for a rocket that is being fired and serve to confine the exhaust gases within the plenum chamber and away from other missile-storage chambers.
There is also the problem of a portion of the rocket exhaust backing up into the chamber of the missile being fired and possibly over-pressurizing that missile chamber.
My own prior U.S. Pat. No. 4,044,648, the entire disclosure of which is incorporated by reference as though fully set forth herein, discloses a pair of hinged doors at the base of each missile storage chamber in the passage connecting the chamber to an associated exhaust plenum duct. The pressure forces on opposite sides of the doors during the firing of a missile are balanced to control the degree to which the doors are opened in order to adjust the opening to the varying dimension of the rocket exhaust stream as the missile rises and leaves the chamber upon firing. As a consequence, the rocket exhaust stream functions as a suitable "gas plug" in the opening in order to prevent recirculation of the exhaust gases back into the chamber undergoing firing.
It is important to control the rocket exhaust gas stream so that the gas plug is effective to prevent recirculation of exhaust gases back into the chamber. Control of the rocket exhaust stream on a dynamic basis to develop the gas plug effect appears to be more effective for the intended purpose than the use of fixed structure such as baffles, valves, diverters or the like which oftentimes have the undesirable result of interfering with the direct exhaust gas stream in their attempt to control flow, limit reverse circulation, etc. My prior U.S. Pat. No. 4,683,798, the entire disclosure of which is incorporated by reference as though fully set forth herein, discloses hinged doors near the lower end of each missile storage chamber but spaced from the juncture with the common plenum chamber by a transition region which provides a smooth transition from a generally square cross-section chamber in which a missile is stored and launched to a round exit opening in the chamber which connects with the exhaust plenum. This enhances the gas plug effect and uses it to prevent recirculation of exhaust gases back into the chamber of the missile being fired.
My prior U.S. Pat. No. 4,686,884, the entire disclosure of which is incorporated by reference as though fully set forth herein, discloses an arrangement including sets of doors to close off missile storage chambers coupled to a common plenum chamber upon the firing of a missile in another chamber with the addition of pivotable deflector panels which are installed in transition sections between the missile storage and launch chambers proper and the common plenum chamber.
Rocket exhaust gas management systems to which the present invention is related incorporate some of the principles which are applicable to the systems of my prior patents cited hereinabove. However, the present invention is intended for use in missile launch systems with multiple launch cells exhausting into a common plenum but with the cells arranged in clusters--e.g., by pairs--sharing common exhaust transition regions before reaching the juncture with the common plenum.
Where two or more missile launch cells share the same duct or flow channel leading into a common plenum, a single aft closure or door for each cell will protect the missile therein from recirculation of the exhaust of its own rocket motor or from exhaust gases from any other rocket which is fired in the launch system. The condition which is required for this arrangement to function properly is that the duct or flow channel leading into the plenum, in combination with the aft closure or door, present an exhaust flow area that causes a gas plug to be formed. This gas plug prevents gases from the plenum from flowing back into the active missile cell. The gas plug is formed when the momentum of the missile rocket exhaust is greater--at every radial position up to the confining wall of the duct and the door or aft closure--than the momentum of the plenum gases flowing back toward the active missile cell opening.
It is important that the aft closure or door be able to open quickly in response to the initial pressure of exhaust gases from the rocket when it is ignited and also to adjust automatically the effective size of the exhaust opening to maintain an effective gas plug as the dimensions of the exhaust plume change, as for example when the missile is flying out of the canister. In addition, the aft closure or door should be capable of closing automatically, preferably in response to gas pressure in the plenum chamber, for those canisters which are not undergoing a missile firing.